[For aMi STACX only] One of the most plaguing issues with Magento when installing a new module or theme is to pay attention to permission changes for files and folders. This normally leads to compile errors, white screens, and/or module install failures.
To resolve permission conflicts simply keep these two commands handy and use them for development environments. For production systems you may want to add additional security restrictions on certain file folders or paths.
A perfect example is to remove the "write" permission on the "etc" directory magento/app/etc/ .
sudo chmod -R u+rwX,go+rX,go-w /var/www/magento
sudo chown -R www-data:www-data /var/www/magento
NOTE: These permissions also apply to the default configurations for all of our stacks.
You should now be good to go!